Thomas Colcombet is a researcher of the CNRS, working in the IRIF institute in Paris. His areas of research are logic, language and automata theory, and games. He has been working on several theoretical models such as tree walking automata, nominal monoids, logics, automata and algebra over infinite words, countable words, and trees, weighted automata, or categorical approaches for the modeling and learnability of automata. He was leader in the development of regular cost functions, an extension of regular languages over words and trees, finite and infinite, used for solving boundedness questions, and which finds applications in language theory, database theory or verification.

Thomas Colcombet also tries to influence the behavior of the community concerning the climate change issue. He is the founder, together with Antoine Amarilli, Hugo Férée and Thomas Schwentick, of the TCS4F initiative.